I have used Mvelopes in the past. It has a “sweep” feature which allows you to rollover unused money to other categories for the next month.
I liked being able to allocate my monthly budgeted amounts to cyber “envelopes” and move money around between envelopes when needed. I also liked how easy it was to allocate 1/12 of any yearly expense (like insurance) to a budget category each month so I wouldn’t spend it on something else. I’m hoping to use the rollover feature in Emma (as it further develops) to help me with those tasks.
I realize that Emma is not an “envelope” budget system. The reason I switched is b/c Mvelopes does not support all of my bank accounts. Emma pulls in EVERYTHING!
I just wanted to add that I would also find out extremely useful to either a) be able to set rolling budgets per category instead of on or off for all categories or b) be able to set an annual budget.
I think one or the other would probably satisfy most users, in practice they seem like a slightly different view on the same thing to me.